Archean Eon

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4.1 Billion Years Ago: Following the late heavy bombardment the first known remains of biotic life are embedded into rocks discovered in Western Australia.

3.9-2.5 Billion Years Ago: The first known cells, resembling Prokaryotes, appear. Unlike modern Prokaryotes these first organisms are believed to have been Chemoautotrophs, meaning they used carbon dioxide as a carbon source and oxidize inorganic materials to extract energy.